Ch 3 - Water

Question 0

Water is polar. Why is this?

Answer 0

Water is composed of covalent bonds where the oxygen atom gets the electrons more regularly than the hydrogen atoms; thus, oxygen takes on a more negative charge while the hydrogen atoms take on a more positive charge

Question 1

How much of a living organisms is comprised of water

Answer 1

60%-90%

Question 2

Hydrogen bonds

Answer 2

Contributes to important properties if water

Question 3

4 of water’s properties that facilitate life

Answer 3

1: Cohesive behavior
2: Ability to moderate temperature
3: Expansion upon freezing
4: Versatility as a solvent

Question 4

Cohesion

Answer 4

Attraction between the same substance

Question 5

Example of cohesion

Answer 5

The hydrogen bonds which hold water molecules together

Question 6

Adhesion

Answer 6

The attraction between different substances

Question 7

Example of adhesion

Answer 7

The attraction between water and plant cell walls

Question 8

What aids cohesion in plants?

Answer 8

Water conducting cels which utilize both the cohesive nature of water and the property if adhesion.

Question 9

Surface tension

Answer 9

A measure of how hard it is to break the surface of a liquid

Question 10

Temperature moderation of water

Answer 10

Water absorbs heat from warmer air and releases stored heat to cooler air. Can also absorb/release a large amount of gear with only a slight change in its own temperature.

Question 11

Specific heat

Answer 11

The amount of heat that must be absorbed or lost for 1g if that substance to change its temperature by 1C.

Question 12

What is the specific heat if water?

Answer 12

1 cal/(g•C)

Question 13

How is heat released/absorbed by water?

Answer 13

Heat is released when hydrogen bonds form. Heat is absorbed when hydrogen bonds break.

Question 14

Heat of vaporization

Answer 14

The heat a liquid must absorb for 1g of of that substance to be converted to gas (water has a high heat if vaporization).

Question 15

Evaporative cooling

Answer 15

As a liquid evaporates, it’s remaining surface cools.

Question 16

At what temperature is water’s density highest?

Answer 16

4C –> water becomes less dense as it becomes a solid at lower temperatures

Question 17

Why is water called the universal solvent?

Answer 17

It can form hydrogen kinds with many other compounds and most biochemical reactions occur in water.

Question 18

Dissociation

Answer 18

The breaking apart of water molecules into ions in an aqueous solution;

Question 19

Ions

Answer 19

Molecules with a net positive or negative charge

Question 20

pH scale

Answer 20

A measure of the acidity or baseness of a solution; the correct balance or H+ and OH- is critical for the proper chemical functioning of organisms.

Question 21

What happens when an ionic compound is dissolved in water?

Answer 21

Each ion is surrounded by a sphere of water molecules. Even large polar molecules such as proteins can be dissolved in water f they have ionic and polar regions

Question 22

What area of our solar system contains the proper temperature range suitable for life and the presence of water?

Answer 22

The band where earth and mars exist

Question 23

What is the focus if astrobiologists seeking life on other planets?

Answer 23

The presence of water.

Question 24

What was recently found in mars?

Answer 24

The presence of ice and recent NASA images suggest the presence of liquid water on the surface of mars.